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All right, let's try again. How many people vote that this is reversible? That looks like a majority to me. Irreversible?
好的，让我们再试试,有多少人认为这是可逆的？,看上去大多数人都这么认为？
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Of course in the reversible case, you're always pushing against an external pressure, which is essentially equal to the internal pressure.
当然在可逆的情况下，外压力，总是，等于内部压力。
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It's been encrypted pretty naively, pretty simplistically, but it's actually an English sentence that's been somehow scrambled; but scrambled in a reversible way.
它被天真地，相当简单地加密了，但是它实际上是一个被加密的英语句子,但是加密方式是可逆的。
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The other beauty about - beautiful thing about proteins is that if you make subtle conformational changes, often those changes are reversible.
蛋白质的另一个美妙之处就是,如果蛋白质发生一些小的构像改变,这些改变通常是可逆的
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So for the reversible process, the work done is the integral under the pressure volume state function, the function of state.
对可逆过程，做的功,是压强体积态函数曲线下，的积分面积。
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Path number 2 on my diagram it's a reversible, this path number 2, it's a reversible constant pressure path.
路径，首先是一个，等压过程。
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it becomes a gray area but it should be pretty clear if you can treat something is reversible are irreversible.
这是个灰色区域,但什么可以当作可逆过程处理,而什么要当作不可逆过程,这是相当清楚的。
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Because it's so important. And I should add and also under reversible work, where the external pressure is equal to the internal pressure.
而且我还要说应该在外部压强,和内部压强相等的,可逆过程中引入它。
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Adiabatic can be either reversible or not, and we're going to do that probably next time or two times.
绝热过程可以是可逆的，也可以不是，我们可能会在下一次或下下次课上,研究这个问题。
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Anybody have any questions on that, because when we voted, the majority of the class thought it was reversible Yes.
上节课我们投票时，多数人都认为它是一个可逆过程，而现在大家应该都知道了,它其实是不可逆过程，有问题吗？
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I mean we can, we can sort of understand why OK, the total energy, if we measure it, we measure a process which is not reversible.
例如我们易于理解为什么，当试图测量一个不可逆系统的总能量，给出的或许。
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So a reversible process leads to requiring certain quantities to be maximized.
因此可逆过程要求,一些物理量要达到最大值。
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Maximum work out is by reversible path.
可逆过程产生最大功。
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One is our Carnot engine as we've seen it, and the other is just any other reversible engine.
一个是我们已经学过的卡诺热机，另一个是任何一个其它可逆热机。
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And what you'll find is that the maximum work out is obtain for a reversible path.
对于各种可能的中间路径，我们将发现,做功做多的是可逆路径。
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Now remember, we went through before how it's a state function but to calculate it, you'd need to find a reversible path, along which you can figure this out.
请记住，我们不需要知道它是怎样的一个态函数,只计算就可以了，你需要找到一条可逆路径，沿着这条路径就能算得这个结果。
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Wrev w reversible. in this case here let's see this is it's a pressure is going down.
曲线下的面积，可逆过程的功,这个过程中。
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So we've got our reversible adiabatic path right.
那么我们有了这条可逆绝热路径。
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So what this says is the efficiency of any reversible engine T1 has to be one minus T2 over T1.
这就是说,任何可逆热机的效率都是,负T2除以。
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And all we know about this is that it's really for some irreversible reversible step.
我们知道,这个式子,对不可逆过程成立。
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that instead of all the steps being reversible, let's just put in one irreversible step.
不是所有的过程都是可逆的，其中有一个过程不可逆。
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So w, the work is less for the irreversible process than the reversible process.
不可逆过程中系统对外界,做的功要比可逆过程时小。
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It's reversible, that means that p external, equals p. I'm doing it very slowly so that I'm always in equilibrium between the external pressure and the internal pressure so I can go back and forth.
我都可以不损失能量，而把过程逆向进行,整个过程中的,每一步都保持平衡,现在我们来分别。
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Let's just take our reversible engine and modify it a little bit.
我们就拿可逆热机为研究对象,并对它进行一点修改。
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The reversible process is going to be colder because it has to expend more energy.
可逆过程降温更多,因为输出的能量更多。
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I can do that because it's reversible, and I can get a functional form out.
画出路径就意味着过程是可逆的，下面我们来看这条曲线的函数形式。
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we're going to have a difference here between the irreversible case and the reversible one.
可逆过程,和不可逆过程,会有不同。
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It's really important that this, that you remember that this is the reversible case.
一定要记住，整个过程是可逆的。
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